Seismic behaviour of creeping landslides at the flanks of water reservoirs

The growing demand for space in mountainous areas due to expansion of infrastructure and housing leads to increased interaction between manmade structures and existing creeping slopes. A special class of problems caused by creeping landslides concerns artificial water reservoirs. Continuous existing movement of the reservoir flanks or reactivation of a dormant creeping landslide due to filling of the reservoir endangers both the reservoir operation and the downstream communities. Reducing the threat posed by the unstable reservoir flanks requires monitoring programs and extensive stabilization works. In order to design stabilization measures and early warning systems, an improved understanding of the landslide mechanics under normal and extreme conditions (heavy rain and earthquakes) is critical.
Existing significant uncertainties with respect to the analysis of landslide behaviour during earthquakes do not allow for reliable assessment of the probability of catastrophic acceleration of the landslide. Such a catastrophic collapse of the landslide into the reservoir lake could cause an impulse wave that can overflow the dam and endanger communities downstream.
The aim of this project is to identify and understand the major effects controlling the seismic behaviour of creeping landslides and hence a first step towards a reliable modelling and risk analysis will be made. The constitutive behaviour of the shear zone is crucial for landslides subjected to earthquakes and will determine whether a catastrophic failure is likely or not.

Swiss Federal Office of Energy

Dr. Marc Kohler